S-({60 -Substituted-arylmethylthio, -arylmethylsulfinyl, and -arylmethylsulfonyl)methylphosphorus esters

ABSTRACT

There are provided novel S-( Alpha -substituted -arylmethylthio, -arylmethylsulfinyl, and -arylmethylsulfonyl) methyl phosphorus esters of reduced mammalian toxicity and methods for controlling insects and acarids therewith. There are also provided methods for protecting plants from attack by insects and acarids by applying an insecticidally or acaricidally effective amount of the aforementioned esters to the foliage of said plants or to the soil in which they are grown.

United States Patent 1191 Wagner, Jr. et al.

[ Dec. 9, 1975 S-( a-SUBSTlTUTED-ARYLMETHYLTHIO, -ARYLMETHYLSULFINYL, AND -ARYLMETHYLSULFONYL)METHYLPHOS- PHORUS ESTERS Inventors: Frank Albert Wagner, Jr.; Roger Williams Addor, both of Pennington, NJ.

Assignee: American Cyanamid Company,

Stamford, Conn.

Filed: Apr. 5, 1974 Appl. No.: 458,376

Related US. Application Data Continuation-impart of Ser. No. 347,308, April 2, 1973, abandoned.

US. Cl. 260/940; 260/948; 260/949;

260/968; 424/210; 424/216 lnt. Cl. C07F 9/165; CO7F 9/40; AOlN 9/36 Field of Search 260/948, 940

References Cited UNITED STATES PATENTS 2,923,730 2/1960 Schrader 260/948 12/1960 Muhlmann et a1 260/948 3,171,853 3/1965 Lorenz et a1 260/948 3,444,274 5/1969 Schrader 260/940 X 3,518,261 6/1970 Nguyen et al.. 260/940 X 3,718,718 2/1973 Addor et al 260/948 FOREIGN PATENTS OR APPLICATIONS 2,119,211 12/1971 Germany 260/948 Primary Examiner-Anton H. Sutto Attorney, Agent, or Firml-larry H. Kline 57 ABSTRACT 12 Claims, N0 Drawings The present invention relates to novel phosphorus esters represented by the structural formula:

wherein R represents a member selected from the group consisting of alkyl from 1 to 4 carbon atoms, alkoxy from 1 to 4 carbon atoms, alkoxyalkyl from 3 to 6 carbon atoms, alkoxyalkylthio from 1 to 4 carbon atoms, phenyl, and NR R R is alkyl from v1 to 4 carbon atoms; R represents a member selected from the group consisting of hydrogen, alkyl from 1 to 4 carbon atoms, mono, di and trihaloalkyl C C, and phenyl; R is alkyl of from 1 to 4 carbon atoms, and when R and R are taken together with the central carbon they may form an al'icyclic ring of from 3 to 8 carbon atoms; R and R each represent a member selected from the group consisting of hydrogen and alkyl C -C A repre- P-SCH Cl K S 4'3- Iiving plants, such as agronomic crops, ornamentals, and the like, by applying a small, but effective, amount of a compound having the aforementioned structures, to the foliage of said plants or to the soil in which they 5 are grown. This invention also contemplates a method for protecting animals from attack by insects andacarids, particularly, fleas and ticks, by topically applying to the host animal an insecticially or acaridally effective amount of a compound of the invention.

10 In accordance with the process of the invention, the

S-(a-substituted-arylmethylthio)methyl phosphorus esters can be prepared by the reaction of an appropriate a-substituted arylmethylthiol with an appropriate S-chloromethyl-substituted phosphorus ester. The re action is preferably carried out in the presence of an alkali metal alkoxide having 1 to 8 carbon atoms and a saturated alcohol having 1 to 8 carbon atoms. However, the reaction may also be conducted in a solvent, such as dimethylsulfoxide or dimethylformamide, in the presence ofa base, such as sodium or potassium hydroxide. Regardless of the solvent system utilized, the reaction can be carried out over a wide temperature range between the freezing and boiling points of the solvent employed, and usually between 0C. and

100C. The reaction can be graphically illustrated as follows:

Y is u 2 KQ1- X R1 1? I Y P-SCH -s-c- 2 R 2 wherein R R R R A, X, Y and Z are as defined hereinabove.

In an alternative procedure, the S-(a-substitutedarylmethylthio)methyl phosphorus esters can be presents a member selected from the group consisting of pared by reacting the appropriately substituted phossulfur and oxygen; n represents an integer from 0 to 2; X and Y each represent hydrogen, alkyl from 1 to 4 carbon atoms (straight or branched chain) or halogen; and Z represents a member selected from the group \l eo consisting of hydrogen, alkyl from 1 to 4 carbon atoms (straight or branched chain), cyano, halogen, alkoxy C to C alkylthio from 1 to 4 carbon atoms, CCl CF carb(lower)alkoxy, nitro and sulfamoyl. The invention is also concerned with a method for controlling insects and acarids with the aforementioned compounds by applying'an insecticidally or acaricidally effective amount thereof to the habitat of said pests. Still more particularly, the invention relates to methods for protecting phorus acid, or the alkali metal or amine salt thereof, with the appropriate chloromethyl thioether. The alkali metal salt reaction may be graphically illustrated as follows, using potassium as the alkali metal:

. A R Y S-CH -S-C- 2 R 0 1 21; wherein R,, R R R A, X, Y and Z are as defined above.

This reaction is preferably carried out in a solvent,

such as a ketone, a chlorinated hydrocarbon, a polyor the like, with or without a dispersanhsurfactant and- /or emulsifyingagent. For application, the concentrate containing about 5 percent to 95 percent by weight of 5 the active phosphorus ester is usually diluted with water or a relatively inexpensive organic diluent, such as deodorized kerosene, and applied as a dilute spray containing from about 0.5 ppm. to about 5000 ppm. of O the active compound.

(II 3 Y R A R H -1 P-SH 011 0 HSC- R2 1 X R A R Y N S C s l 0 H2 I Z R R 1 To convert the above-prepared S-(a-substituted-aryl- 25 Suitable solid adjuvants include, for instance, attamethylthio)methyl phosphorus ester to the corresponding sulfoxide, said ester can be treated with an equivalent amount of m-chloroperbenzoic acid in the presence of a solvent, such as methylene chloride. Mixing of the reactants is preferably conducted at a temperature between about 0C. and C., followed by warming to temperatures between C. and 40C.

Conversion of an S-(a-substituted-arymethylthio)- methyl phosphorus ester to the corresponding sulfone can readily be achieved either by the reaction of said ester with potassium permanganate in aqueous tertbutyl alcohol employing magnesium sulfate as a buffer, or by reaction with two equivalents of m-chloroperbenzoic acid in a solvent, such as methylene chloride. The

formation of the desired sulfoxides and sulfones of the 40 corresponding phosphorus esters also can be achieved through the use of other oxidizing agents well known in the art such as sodium metaperiodate, hydrogen peroxide, phthalic monoperoxy acid, other peracids, and chromic acid.

The compounds of the present invention are highly effective insecticidal and acaricidal agents. They may be applied with conventional type applicators as contact, soil or systemic insecticides and acaricides and may be used in combination with a wide variety of adjuvants and formulation aids. They may be advantageously employed in combination with solid or liquid adjuvants in the form of granular formulations, wettable powders, emulsifiable concentrates, dusts, dust concentrates, and the like. The compounds of this invention also have the advantage that they exhibit extended or enhanced residual insecticidal and acaricidal effectiveness. Further, they can be applied by utilizing ultra low volume techniques as in US. Pat. No. 3,515,782.

With conventional type formulations, the active ingredient can be initially formulated as a concentrated composition, comprising a substantial amount of the active ingredient and a minor amount of solid or liquid adjuvant which serves as a formulation aid or condi- 65 tioning agent, permitting the concentrates to be further mixed with a suitable solid or liquid carrier.

Useful liquid adjuvants in which the toxicant can be dissolved, suspended or distributed include, for example, xylene, benzene, lower aliphatic alcohols, fuel oil.

pulgite, kaolin, talc, diatomaceous earth, silica, corn cob grits, coconut shell, or the like, in granular or finely ground form. The active ingredient can be conveniently formulated with the solid adjuvants as dusts,

dust concentrates, wettable powders, granulars, and

the like.

Dusts are generally prepared by mixing or grinding together from about 1 percent to 10 percent by weight of the active ingredient with the finely divided solid inert'diluent. These formulations can then be applied with dusting equipment to the foliage of agronomic crops or fields, meadows, forests, or the like, which are to be protected from insect attack. In practice, it is generally sufficient to provide between about 0.125 pound and pounds per acre of active material.

Dust concentrates are usually prepared in the same manner as dusts. However, from about 25 percent to 75 percent by weight of the active compound, and from 75 percent to 25 percent by weight of diluent are generally used.

wettable powders are prepared in the same fashion as the dust concentrates; however, from about 1 percent to 5 percent by weight of an emulsifying or surface active agent, and from about 1 percent to 5 percent by weight of a dispersing agent are usually included in such formulations. Polyethylene glycols, methoxy polyethylene glycols, sodium lignosulfonate, calcium dodecylbenzene sulfonat polyoxyethylated vegetable oil, alkyl phenoxy polyoxyethylene ethanol, and the like, are among the surfactants, emulsifying agents and dis- 6() persing agents which can be used in these formulations.

In practice, the wettable powders are generally dispersed in water and applied as a dilute spray to the vegetation, soil or habitat where insect and/or acarid control is desired.

lnsect and acarid control and plant protection in fields, forests, crop lands, and the like, are generally achieved with the compounds of the present invention applied at rates of from about 0.25 pound to about 8 pounds per acre.

Advantageously, the compounds of the present invention exhibit a high order of pesticidal activity and low mammalian toxicity. The increased margin of safety with respect to manufacture, handling and storing obtained with compounds of the present invention is particularly significant, since spray application is feasible with these compounds where such is not true or is significantly more hazardous in the case of closely related prior art compounds.

The invention may be better understood by referring to the examples provided below which are taken as merely illustrative. Unless otherwise specified, the parts are given by weight and the analysis is in percent.

EXAMPLE 1 Preparation of the Intermediate: a, a-Dimethyl a-toluenethiol To 227 ml. of 48 percent hydrobromic acid (2.00 mole), cooled to C. to 5C., is added 76.1 grams (1.00 mole) of thiourea; a considerable amount of the thiourea dissolves. To the stirred slurry is carefully added 136 grams (1.00 mole) of a,a-dimethylbenzyl alcohol, during 2 hours. The reaction mixture temperature is controlled at 25C. to 30C. with an ice bath during the addition. After about one-third of the alcohol has been added, the mixture becomes extremely thick; at this point an additional 1 14 ml. of the concentrated acid is added (total 341 ml., 3.00 moles) and the alcohol addition is completed. To the thick reaction mixture is added 400 grams of crushed ice, resulting in a strong endotherm, and the mixture is stirred until the ice melts. This mixture, still at 0C., is filtered on a sintered glass funnel and the filter cake is washed with ether and stored in vacuo over potassium hydroxide overnight. The isothiouronium salt solids weighing 280 grams, apparently still wet, exhibit a melting poing range from 84C. to 94C. The yield is essentially quantitative.

A solution of 60 grams (1.5 moles) of sodium hydroxide in] .2 liters of water is next prepared, which results in a solution temperature of C. The above prepared isothiouronium salt is added immediately (no detectable exotherm), and the mixture is stirred overnight. To this rapidly stirred mixture is added 200 ml. of ether, and this mixture is made strongly acidic by the slow addition of 50 ml. of concentrated hydrochloric acid with cooling. The organic layer is collected. The aqueous layer is extracted with two 200 ml. portions of ether. The three organic layers are combined, washed with two 100 ml. portions of saturated sodium chloride solution, and dried over magnesium sulfate. Evaporation of the ether from the dried solution, at 30C./12 mm. Hg., gives 128 grams (84.3 percent based on alcohol) of clear, mobile liquid with a faint yellow cast. Distillation through a simple head gives the pure product a,a-dimethyl a-toluenethiol; boiling point 63C. to 64C/2.3 mm. Hg.

EXAMPLE 2 Preparation of S-(a,a-dimethylbenzylthio)methyl 0,0-Diethyl Phosphorodithicate To 15.2 grams (0.100 mole) of a,a-dimethyl-atoluenethiol in 50 ml. of tert-butyl alcohol is added 11.2 grams (0.100 mole) of potassium tert-butoxide. The solution is cooled to room temperature and is added slowly to a solution of 23.5 grams (0.100 mole) of S-chloromethyl 0,0-diethyl phosphorodithioate in 50 ml. of tert-butyl alcohol. A slow, mild exotherm ensues. The temperature of the reaction mixture is maintained at 25C. to 30C. with a water bath. The reaction mixture is stirred at room temperature for 20 hours, and then the solvent is removed at 35C. and 12 mm. Hg. The residue is partitioned between 150 ml. of methylene chloride and ml. of 1.7 potassium hydroxide solution. The organic phase is washed with a solution prepared from 25 ml. of 5 percent potassium hydroxide plus 25 ml. of saturated sodium chloride solution then with three 25 ml. portions of saturated sodium chloride, two 25 ml. portions of 5 percent hydrochloric acid, three 25 ml. portions of saturated sodium chloride, 25 ml. of 5 percent potassium hydroxide, and three 25 ml. portions of saturated sodium chloride. The organic phase is dried with magnesium sulfate, and the solvent removed, ultimately at 60C./O.5 mm. Hg., to give 30.9 grams (88.3 percent) of moderately viscous, clear, straw-colored liquid. This material is dissolved in carbon tetrachloride and placed on a 2%inch i.d. column containing 20 inches of 60 to 100 mesh Florisil magnesium silicate. The column is eluted with 1.5 liters of carbon tetrachloride, then successively with one liter portions of 5, 10, 15, 20 and 25 volume percent methylene chloride in carbon tetrachloride, and finally with one liter of methylene chloride. The residue obtained from the removal of the solvents from the last three e'ffluent fractions is a clear, faintly straw-colored, moderately viscous liquid with n =l.5706, a theoretical proton magnetic resonance integral, and the following analysis. 1

Analysis. Calculated for C H O PS C, 47.98; H, 6.61 S, 27.44. Found: C, 48.19 and 48.24; H, 6.57 and 6.63; S, 27.73 and 27.71.

The solvents are evaporated from the three effluent fractions preceding those worked up above, and from a 1.5 liter methylene chloride fraction, following those worked up above, to give additional material which appears to be of quality equivalent with that obtained above, by thin-layer chromatographic analysis. Total yield 13.9 (40 percent).

EXAMPLE 3 Preparation of S-(a,a-Dimethylbenzylthio)methyl 0,0-Diethyl Phosphorodithioate To a solution of 43.7 grams (0.234 mole) of 0,0- diethyl phosphordithioic acid and 47.0 grams (0.234 mole) of chloromethyl a,a-dimethylbenzyl sulfide (which is prepared, for example, by the reaction of the thiol, paraformaldehyde and gaseous hydrogen chloride in methylene chloride at low temperature) in 200 ml. of methylene chloride is added, dropwise, a solution of 23.7 grams (32.7 ml., 0.234 mole) of triethylamine in 50 ml. of methylene chloride. The addition is carried out during 20 minutes, and the reaction mixture temperature is maintained at 20C. to 25C. with an ice bath. The mixture is stirred at room temperature for 2.5 hours (an extremely mild, slow exotherm is noted during the early part of this period) and is then heated at reflux for 30 minutes. The cooled reaction mixture is washed with 50 ml. ofwater, 25 ml. of 5 percent hydrochloric acid, 25 ml. of saturated sodium chloride solution, 25 ml. of 5 percent potassium hydroxide solution, and two 25 ml. portions of saturated sodium chloride. The solvent is removed from the dried (magnesium sulfate) solution to give 76.0 grams (92.7 percent) ofpalc yellow liquid. Comparison of the proton magnetic resonance spectrum of this material with that of the analytical sample, above, shows this present sample to be approximately wt. percent the desired product.

7 EXAMPLE 4 Preparation of S-(a,a-Dimethylbenzylthio)methyl 0,0- Diethyl Phosphorodithioate A mixture of 37.2 grams (0.200 mole) of O,O-diethyl phosphorodithioic acid, 30.5 grams (0.200 mole) of a,a-dimethyl a-toluenethiol and 16.5 ml. (0.220 mole) of methanol-free formalin is stirred vigorously atroom temperature for three days. The mixture is extracted with 250 ml. of methylene chloride, and this solution is washed with two 30 ml. portions of saturated sodium chloride solution, four 30 ml. portions of 5% potassium hydroxide solution, and three 30 ml. portions of satu rated sodium chloride. Evaporation of the solvent from the dried (magnesium sulfate) solution gives a colorless, moderately viscous liquid residue. The proton magnetic resonance spectrum of this material establishes that the desired product is the major component.

EXAMPLE 5 Preparation of S-(a,a-Dimethylbenzylthio)methyl 0,0-Dimethyl Phosphorodithioate To 0.078 mole of chloromethyl a,a-dimethylbenzyl sulfide in 100 ml. of acetone is added 15.3 grams (0.078 mole) of sodium 0,0-dimethyl phosphorodithioate followed by stirring overnight. The reaction mixture is maintained at a temperature of C. to C.

The acetone is evaporated, the residue is suspended in 200 ml. of methylene chloride, and the organic solution washed with water and 5 percent sodium hydroxide solution. The organic solution is dried with magnesium sulfate. Evaporation of the solvent gives 25.0 grams (99 percent) of a colorless liquid. This material is chromatographically purified on a silica gel drycolumn using 25 volume percent methylene chloride in hexane as the eluant. 9.2 grams of colorless liquid is obtained, with proton magnetic resonance and infrared spectra confirming the assigned structure.

Analysis. Calculated for C H O PS C, 44.72; H, 5.90. Found: C, 44.54; H, 6.00.

EXAMPLE 6 Preparation of S-(p-Chloro-a,a-Dimethylbenzylthio )methyl 0,0-Diethyl Phosphorodithioate To 32.5 g. of chloromethyl p-chloro-a,a-dimethylbenzyl sulfide (prepared from p-chloro-a,a-dimethyl a-toluenethiol obtained as in Example 1 from p-chlorooz,a-dimethylbenzyl alcohol) in 250 ml. of acetone is added 23.4 g. of potassium 0,0-diethyl phosphorodithioate. After stirring the mixture for several hours at room temperature the bulk of the acetone is removed under vacuum and the residue is mixed with methylene chloride. The methylene chloride mixture is washed with water and then dried over magnesium sulfate. Removal of solvent under vacuum leaves 38.2 g. of crude product which is purified by the dry-column technique on a 1.5 inch diameter column of silica gel using 25 percent methylene chloride in hexane as the developing solvent and ultraviolet light for detection. A major band, out from the column and eluted with ethyl acetate, affords l2.8 g. colorless product on concentration. It is homogeneous by thin layer chromatography and the structure is consistent withboth the infrared and proton magnetic resonance spectra.

Analysis. Calculated for C H CIO PS; C, 43.70; H; 5.72. Found: C, 43.59; H, 5.72.

8 EXAMPLE 7 Preparation of S-(p-Chloro-a,a-dimcthylbenzylthio)methyl 0,0,-Dimethyl Phosphorodithioate Following the procedure of Example 6, but substituting potassium 0,0-dimeth.yl phosphorodithloate for potassium 0,0-diethyl phosphorodithioate, gives the purified product as a colorless oil.

Analysis. Calculated for C H CIO PS C, 40.40; H, 5.05. Found: C, 40.13; H, 5.12.

EXAMPLE 8 Preparation of S-( 3 ,4-Dichlor o-a,a-dimethylbenzylthio )methyl 0,0-diethyl Phophorodithioate Using 3,4-dichloro-a,a-dimethyl-a-toluenethiol pre- 20 pared from 3,4-dichloro-a,a-dimethylbenzyl alcohol by the procedure of Example 1 and following the procedure of Example 6, the desired product is obtained as a colorless oil.

Analysis. Calculated'for C H Cl O PS C, 40.11;

25 H, 5.01; Cl, 16.92; P, 7.39; 5, 22.94. Found: C, 39.97;

H, 5.07; Cl, 17.06; P, 7.30; S, 23.04.

EXAMPLE 9 Preparation of S-(a,a-Dimethyl-2,4,5-trichlorobenzylthio)-methyl 0,0-Diethyl Phosphorodithioate Using a,a-dimethyl-2,4,5-trichloro-a-toluenethiol prepared from a,oz-dimethyl-2 ,4,5trichlorobenzyl alcohol by the procedure of Example 1, and following the procedure of Example 6, the desired product is obtained as a colorless oil.

Analysis. Calculated for C H CI O PS3: C, 37.06;

H, 4.41. Found: C, 38.40 and 38.23; H, 4.33 and 4.33.

EXAMPLE 10 Preparation of S-(2,5-Dichloro-a,a-dimethylbenzylthio )-methyl Q,O-Diethyl Phosphorodithioate EXAMPLE ll Preparation of 'S-( 3 ,4-Dichloro-oz,a-dimethylbenzylthio )methyl 0,0-Dimethyl Phosphorodithioate Using 3,4dichloro-a,a-dimethyl-a-tolucnethiol prepared from 3,4-dichloro-rx,a-dimethylbenzyl alcohol by the procedure of Example 1, and using potassium 0,0- dimethyl phosphorodithioate in place of potassium 0,0-dicthyl phosphorodithioate. the procedure of Example 6 gives the desired product as a-colorlcssoil. 1 Analysis. Calculated for C H CI O PS C. 36.84; H, 4.35. Found: C. 36.83; H, 4.34.

EXAMPLE 12 Preparation of S-(a,a-Dimethylbeniylthio)methyl O-Ethyl S-Propyl Phosphorodithioate Proceeding in the same manner as Example-5, and

substituting sodium O-ethyl S-propyl phosphorodithioate for 0,0-dimethyl phosphorodithioate, gives. the expected product as an oil. Analysis. Calculated for C, H PO S C, 49.45; H, 6.86. Found:- C, 49.23; H,

EXAMPLE 13 Preparation of S-(p-Bromo-a,a-dimethylbenzylthio)methyl 0,0-Dimethyl Phosphordithioate EXAMPLE 14 Preparation of S-(m,a,a-Trimethylbenzylthio)methyl 0,0-Diethyl Phosphorodithioate Using in, a,a-trimethyl-a-tolueneth'iol prepared from m,a,a-trimethylbenzyl alcohol by the procedure of Example 1 and following the procedure of Example 6, the desired product is obtained as a colorless oil.

Analysis. Calculated for C H O PS C, 49.45; H,

6.86. Found: c, 49.54; H, 6.85.

EXAMPLE 15 Preparation of S-(a-Methylbenzylthio)methyl 0,0-Diethyl Phosphorodithioate Following the same procedure as in Example 4, but substituting a-methyl-a-toluenethiol for a,a-dimethyla-toluenethiol, and effecting purification with column chromatography, there is obtained the desired product as a colorless oil.

Analysis. Calculated: C, 46.43; H, 6.24. Found: C, 46.42; H', 6.05.

Example 16 Preparation of S-(p-Chloro-a,a-dimethylbenzylthio)methyl O-methyl S-Methyl Phosphorodithioate EXAMPLE 17 Preparation of S(a,a-Dimethylbenzylthio)methyl O-Methyl Phosphoramidothioate 1 Following the procedure of Example 5, potassium 0- methyl phosphoramidothioate gives the desired product.

, EXAMPLE 18 Preparation of S-(a,a-Dimethylbenzylthio)methyl O-Methyl S-Z-Metho'xyethyl phosphorodithioate Following the procedure of Example 5, potassium S- Z-methoxyethyl O-methyl phosphorodithioate gives the desired product. Compounds of this type also are obtained by demethylation of the 0,0-dimethyl ester of S-(a,a-dimethylbenzylthio)methyl phosphorodithioic acid (Example 5) by known methods (for example, with hydrosulfide ion, tertiary amine bases, O,O-diisopropyl phosphorodithioate ion, iodide ion), and realkylation of the intermediate O-methyl S-(a,d-dimethylbenzylthio)methyl phosphorodithioate with an appropriate alkyl or substituted alkyl halide.

EXAMPLE 19 Preparation of S-(a,a-Dimethylbenzylthio)methyl O-lsopropyl O-Methyl Phosphordithioate 1 Following the procedure of Example 5, potassium 0- methyl O-isopropyl phosphorodithioate gives the desired product. Alternatively, this compound is obtained by hydrolysis of the 0,0-diethyl ester of S-(a,a-dimethylbenzylthio)methyl phosphorodithioic acid of Example 2 (for example, with an aqueous alkali metal hydroxide) and subsequent reaction of the formed (01,01- dimethylbenzylthio)methanethiol with O-methyl O-isopropyl phosphorochloridothioate, in the presence of, for example, alkali metal alkoxides or tertiary amines.

EXAMPLE 20 Preparation of S-(a,a-Dimethylbenzylthio)methyl 0,0-diisopropylPhosphorodithioate EXAMPLE 21 1 Preparation of S-(a-Ethyl-a-methylbenzylthio)methyl 0,0-Diethyl Phosphorodithioate To 0.091 mole of chloromethyl a-ethyl-a-methylbenzyl sulfide and 16.9 grams (0.091 mole) of the phosphorodithioate of the formula (C H O) PSSH in 100 ml. of ether is added 9.2 grams of triethylamine, dropwise, maintaining the temperature at 25C. The mixture is stirred for several hours and then washed with water and 5 percentsodium hydroxide solution. Evaporation of the solvent from the dried (magnesium sulfate) solution gives 31.3 grams (95 percent) of a colorless liqiuid. This material is chromatographically purified on a silica gel dry-column using 10 volume percent methylene chloride in hexane as the eluant.

6.3 Grams of liquid is obtained with proton magnetic resonance and infrared spectra indicating analytical purity.

Analysis. Calculated for C, H O PS C, 49.45; H, 6.86. Found: C, 49.32; H, 6.91.

An additional 6.0 grams ofliquid of estimated percent to percent purity also is obtained.

EXAMPLE 22 Preparation of S-(a,a-Diethylbenzylthio)methyl 0,0-Diethyl Phosphorodithioate In similar manner but substituting chloromethyl 01,01-

diethylbenzyl sulfide for the chloromethyl d-ethyl-amethylbcnzyl sulfide, there is obtained the'desired product.

Analysis. Calculated: C, 50.79; H, 7.14. Found: C, 50.81; H, 7.31.

EXAMPLE 23 Preparation of S-( 2 ,3 -Dichloro-oz,a-dimethylbenzylthio)methyl 0,0-Dimethyl Phosphorodithioate EXAMPLE 24 Preparation of S-(p-Cyano-a,a-dimethylbenzylthio)methyl 0,0-Dimethyl Phosphorodithioate Following the procedure of the above Example, using chloromethyl p-cyano-a,a-dimethylbenzyl sulfide, gives the purified product as a colorless oil.

Analysis. Calculated for C H NO PS C, 44.96; H, 5.18; N, 4.03. Found: C, 44.57; H, 5.39; N, 3.82.

EXAMPLE 25 Preparation of S-(2,5-Dichloro-a,a-dimethylbenzylthio) methy 0,0-Dimethyl Phosphorodithioate In similar manner, using chloromethyl 2,5-dichloroa,a-dimethylbenzyl sulfide, the purified product is obtained as a colorless oil.

Analysis. Calculated for C H Cl O PS C, 36.84; H, 4.35. Found: C, 38.64; H, 4.42.

EXAMPLE 26 Preparation of S-(p-Methylthio-a,a-dimethylbenzylthio)methyl 0,0-Dimethyl Phosphorodithioate In similar manner, using chloromethyl p-methylthioa,a-dimethylbenzyl sulfide, the purified product is obtained as a colorless oil.

Analysis. Calculated for C H O PS C, 42.39; H, 5.70. Found: C, 42.66; H, 5.71.

EXAMPLE 27 Preparation of S-((1,0:-Dimethylbenzylsulfinyl)methyl 0,0-Diethyl Phosphorodithioate A solution of 20 grams (0.057 mole) of the phosphorodithioate product of Example 2 in 100 ml. of methylene chloride is cooled to 5C. to 10C., and 1 1.6 grams of 85 percent m-chloroperbenzoic acid is added protion-wise during 15 to 20 minutes. The reaction mixture temperature is maintained at 10C. during the addition.

The heterogenous mixture is stirred overnight at room temperature, and then filtered. The filtrate is washed with sodium carbonate solution and dried with magnesium sulfate. Evaporation of the solvent gives 20.9 grams of a pale yellow liquid (100 percent yield). This material is chromatographically purified on a silica gel dry-column, using methylene chloride as the eluant.

7.5 Grams of a colorless liquid is obtained, with proton magnetic resonance and infrared spectra sutstantiating thee assigned structure.

Analysis. Calculated for C H O PS C, 45.90: H, 6.28. Found: C, 44.67; H, 6.06.

EXAMPLE 28 Preparation of S-(a,a-Dimethylbenzylsulfinyl)methyl 0,0-Diisopropyl Phosphorodithioate The procedure of the above example is employed except that 0,0-diisopropyl S-(a,a-dimethylbenzylthio)- methyl phosphorodithioate is substituted for the 0,0- diethyl S-(a,a-dimethylbenzy1thio)methyl phosphorodithioate, and gives the desired product.-

Analysis. Calculated: C, 48.73; H, 6.85. Found: C, 48.87; H, 6.85.

EXAMPLE 29 Preparation of S-(a,a-Dimethylbenzylsulfonyl)methyl 0,0-Diethyl Phosphorothioate To a solution of 0,0-diethyl S-(ot,a-dimethylbenzylthio)methyl phosphorothioate (0.050 mole) in 100 ml. of methylene chloride, cooled to 0C. to 5C., is added the solid m-chloroperoxybenzoic acid (20.4 grams of assumed percent purity, 17.3 grams real, 0.10 mole) during one hour; the temperature of the exothermic reaction is maintained at 5C. to 10C. during the addition with external cooling. The reaction mixture is stirred for several minutes at ca. 5C., allowed to warm, and then stirred at room temperature overnight. The mixture is filtered and the filtrate is washed with 50 ml. of 2N sodium hydroxide, 25 ml. of 2N sodium hydroxide, two 25 ml. portions of saturated sodium chloride and dried (magnesium sulfate). Reduced-pressure evaporation of the solvent from the dried solution gives a moderately viscous liquid.

Sulfide Product Phosphorodithioic acid, S- (p-ehloro-m.u.a-trimethy1- benzylthio)methyl 0,0- diethyl ester Phosphorodithioic acid, S-' (p-cyano-ma-dimethylbenzyb thio)methyl 0,0-diethyl ester Chloromethyl p-chloro-ni,a. a-trimethylbenzyl sulfide Chloromethyl payano-madimethylhenzyl sulfide EXAMPLE 31 In a manner similar to that used in Example 5, the following sulfides are substituted for chloromethyl madlmethylbenzyl sulfide to yield the products hereinbelow:

Sulfide Product Phosphorodithioic acid, S- (a,a-dimethyl-p-nitrobenzylthio)methyl 0.0-dimethyl Chloromethyl mot-dimethyl p-nitrobenzyl sulfide liters of solution ispipetted onto a standard volume of dust in one-ounce jars, and the acetone allowed to evaporate. Twenty-five milliliters of moist soil and about three wheet seeds are placed in the jar, capped,

. 5 CSIBI' Substituted I'or p-nitro Substitute for p-nitro n the contents thoroughly mlxed- Ten False wlre' l t ,fl h l l T h l worm larvae (Eleodes suturalis), ten days old, are then 2: -liuti m y j{.fi ,,f, y I placed in each jar. Mortality counts are made after 6 3. -p-isopropyl- -p-isopropyl days and percent mortality determined. Data obtained 4. -m-carbethoxy- -m-carbethoxy 5. -p-trichloromethyl- -p-trichloromethyll0 drc provlded m Table I below.

Southern Corn Rootworm Control EXAMPLE 32 Compounds are prepared as dusts on tale. The com- Preparation of pounds are dissolved in acetone, and appropriate rates S-(a,aDimethyIbenzylthio)methyl-N,N,O-trirnethylobtained by serial dilution. One and one-quarter milliphosphoramidodithioate liters of solution is pipetted onto a standard volume of TABLE I Compound R A R II I P -SCH (0) -c- Rateof 2 l Application R 0 R4 2 lbs/Acre Potting Soil R R n R;, R, A X Y Z 50 1 Percent Control of False Wireworms C H 0 C,H 0 H CH 5 H H H 100 I00 0 C H O C H 1 CH CH 5 H H H 100 100 0 CH O CH 0 CH CH 8 H H H 100 100 100 cH ncHo (CH=,) CH 0 CH CH 5 H H H 100 0 C,H ,O C H 0 CH CH 5 H H H 100 100 0 Percent Control of Southern Corn Rootworm Larvae C H 5O C,H 0 i H CH3 S H H H I00 I00 80 c H o C H 1 CH CH 5 H H H 100 100 0 CH O CH 0 CH CH 3 H H H 100 I00 100 (CH3)2CHO (CH3)2CH 0 CH3 CH3 S H H H 100 0 C,H,,O C H 0 CH CH 8 H H H 100 I 00 90 C H 0 c,H 0 CH C H s H H H I 00 100 0 C,H,,O C,H5 0 C2H5 C2H5 S H H H I00 I00 n-C H,S c H 0 CH CH 0 H H H I00 I 00 0 C,H,,0 C H,, 0 C CH 5 H 4Cl H 100 90 0 C H O C,H 0 CH CH 5 H 3CH H 100 100 I00 CH O CH1, 0 CH1 CH3 S 3C1 4Cl H 100 I00 I00 CHQO CH3 0 CH1, CH3 S H 4Cl H I00 I00 I00 CH3S CH 0 CH3 CH3 0 H 4Cl H 100 I00 0 cH,,o cH 0 CH CH 5 H 4Br H 100 I00 90 CH,,0 CH 0 CH CH 5 H 4CN H 100 100 0 CH;,O CH3 0 CH3 CH3 S H 2Cl 5Cl I00 I00 0 CH5O CZH5 0 CH CH;, 5 2Cl SCI H I00 I00 CH=,0 CH 0 CH CH 5 2CI H 3Cl I00 90 60 Following the procedure of Example 5, but replacing dust in I-ounce jars, and the acetone allowed to evaposodium 0,0-dimethyl phosphorodithioate with potasrate. Twenty-five milliliters of moist soil and about 200 sium N,N,O-trimethyl phosphoramidothioate affords millet seeds are placed in the jar, capped and the conthe subject compound. tents thoroughly mixed. l0 second-instar larvae of the EXAMPLE 33 Southern corn rootworm (Diabrotica undecimpunctata) are then placed in each jar. Mortality counts are Preparation of made after 6 days and percent mortality determined. S-(3,4-Dichloro-a,a-dimethylbenzylthio)methyl-O- Data obtained are provide in Table 1 below.

ethyl Phenylphosphonodithioate By the reaction of chloromethyl 3,4-dichloro-a,a- EXAMPLE 35 il ay g itl Sulfide g Sodium 'z p y' Control of Insects and Acarids 0s ono it ioate the su 'ect com oun is re are p p 1 p p p The efficacy of the compounds of the present inven- EXAMPLE 34 tion for controlling insects and acarids is demonstrated Insecticidal Evaluation (False Wireworm Control) Compounds are prepared as dusts on tale. The compounds are dissolved in acetone, and appropriate rates obtained by serial dilution. One and one-quarter milliin the following tests. Procedures employed in these tests are provided below as procedures A through H, and data obtained are reported in Table II.

A. Tarnished Plant Bug Lygus lineolaris (Palisot de Beauvois) Test compounds are prepared as 1000 ppm. solutions in l() percent acetone. 0.2 percent Alrodync 3 15, and 89.8 percent water. A tenfold dilution is made with 65 percent acetone and 35 percent water. The

petri dish. The dishes are covered and held at 80F. and 50 percent R.H. After 2 days, mortality counts are made.

(Koch) Sieva lima bean plants with primaryleaves 3 to 4 inches long are infested with about 100 adult mites per leaf 4 hours before use in this test. The mite primary leaves ofSieva lima bean plants are dipped 5 and egg infested plants are dipped for 3 seconds in for 3 to 5 seconds in the test solutions and placed in h Same m i d i h hid test, d h a CXhllUSl htmtl it) ry when y, each lcilf is r plants set in the hood to dry. They are held for two placed in a 4-inch petri dish with a moist filter d t 80F, 60 er ent RH, and the adult mite pape on t l bottom TCn u t Lygu g M H) mortality estimated on one leaf under a steroscopic pirated from the stock culture and placed in the microscope. The other leaf is left on the plant an petri dish. The dishes are covered and held at 80F. additional five days and then examined at X and 50 percent R.H. AfterZdays, mortality counts power to estimate the kill of eggs and of newly are made. hatched nymphs, giving a measure of ovicidal and B. Boll Weevil Anthonomus grandis (Boheman) id l tion, respectively.

Test compounds are prepared as l()()() ppm. solutions H F M i B B tl E ilaehna varivestis (Muls.) in 10 percent acetone, 0.2 percent Alro yn 31 Compounds to be tested are made up as 100 or to and 89.8 percent water. A tenfold dilution is made l ti i 65 r ent acetone/3S percent with 65 percent acetone and 35 percent wat r. The water. Sieva lima bean leaves are dipped in the test first or second true leaf of young cotton plants is l ti d t in the hood to dry. When dry, they dipped for 3 to 5 seconds in the test solution and are l d in 4 in h etri dishes which have a moist placed n an exhaust hood to y- When y, each filter paper in the bottom, and ten third-instar bean leaf is Plhccd in 11 4-inch Pctri dish with a beetles are added to each dish. The dishes are covter paper on the bottom. Ten adult boll weevils are d d h ld at 80F, 60 er ent R,H. After 2 rcmnvcd from the Stock Culture and Placed in the days, mortality counts and estimates of the amount of feeding are made. Compounds showing kills greater than 75percent are further tested at tenfold dilutions in 65 percent acetone/35 percent water.

Bcah APhlS Aphls hlhac (Scopoh) G. Western Potato Leafhopper Empoasca abrupta Compounds are tested at I00, I() and 1 ppm. in solu- (Say) tion or suspension in 65percent acetone/35percent Sicva i bean plants i h primary l f water, Two-inch fiber pots each containing a nasturtium plant 2 inches high and infested with about 150 aphids 2 days earlier, are placed on a turntable (4RPM) and sprayed for two revolutions with a No. I54 DeVilbiss Atomizer at 20 psi. air pressure. The spray tip is held about 6 inches from the plants, and the spray is directed so as to give complete coverage of the aphids and the plants. The sprayed plants are laid on their sides on white enamel trays.

panded to 3 to 4 inches are dipped into 100 or 10 ppm. 50 percent acetone/5t) percent water solutions and set in the hood to dry. A l-inch piece of the tip of a treated leaf is cut off and placed in a 4- inch petri dish with a moist filter paper in the bottom. From three to ten second-instar nymphs are tapped from the culture plants into the test dish and rapidly covered. Mortality counts are made after two days at 80F, and 50 percent R.H.

Mortality estimates are made after holding for two Malaria Mosquito AnophclcS quudrimaculatus days at 70F. and percent R.H. (Say) Adult Test southern Armyworm Pmdchla erldahiu (Cramcr) Solutions of percent acetone/35 percent water CompoundS are tested at 1000 and PP in containing 10 ppm. of test compound are poured tion or suspension in 65 percent acetone/35 perinto wide-mouth 2-ounce jars, each containing a watch Sim/a hhjla bean P fy leaves f 45 microscope slide. The slides are removed from the PP for 3 seconds In the test 501mm and Set h test solution with forceps and laid horizontally to a hoodfm hcrcch h yh y h 'f dry on a wide mouth 4-ounce bottle. When dry, Placed a 4'1hch P dish Whlch has a mom filter they are placed in the same 4-ouncc bottle and ten P p in the hOttQm tch thlrdjlhstar armywmm 4- to S-day-old mosquitoes of mixed sexes are larvae about 3/8 Inch long- The dlshcs are Covered added to each bottle. A piece of cotton gauze held 11nd held at 3003, and 60 p f After two on by an elastic band serves as a lid, and wad of days, mortahty Counts and eshmatcs of h amount cotton soaked in 10 percent honey solution serves of fccdlhg are compohhds Showlhg Partial food. Mortality counts are made after one day at kill and/or inhibition of feeding are held an extra 0 50 percent (relative humidity) Dam y for further obscrvahohsobtained with the above procedures are reported in E. Two-spotted Spider Mite Tctranychus urticae Table 1 below TABLE ll Control of Insects and Acarids Percent Mortality Compound Tarnished Boll Bean Southern Plant Bug Weevil Aphid Armyworm nn PP pp W lot) too ltlt) to 1 7 i000 too it cH 4 l (c H o -P-SCH s 94 9s lllll too its lot) too TABLE lI-continued Control of Insects and Acarids Percent Mortality Twospotted Mexican Western Spider Bean Potato Malaria Mite Beetle Leafhopper Mosquito PP PP'"- PP'- PP 300 I I00 I0 I00 l0 l0 6 100 90 0 100 50 30 7 0 0 60 lOO 9O 8 100 100 80 0 I00 I00 9 O 0 O 100 0 70 i0 0 90 O O O l l 100 100 80 0 100 O 0 l2 0 0 0 13 100 I00 100 40 100 100 75 I4 100 100 0 I00 0 75 I5 100 100 30 0 100 0 0 I6 100 100 30 0 100 0 67 i7 I00 I00 50 O 100 O 100 l8 50 0 40 0 100 0 0 endin on the viscosit of the material. If the material EXAMPLE 36 P g y Mammalian Toxicity Studies (LD for Rats and Mice) Twenty male albino rats or mice of the Carworth Farms Nelson strain (CFI strain for mice) (or other suitable strain) weighing approximately 90 to 120 grams (l8 g. for mice) are selected. Basically, these animals are fasted 24 hours before dosing. Mice are not fasted.

For materials which are soluble oreasily dispersed in an aqueous medium, a 20 percent solution or suspension is prepared in an aqueous solution of 0.2 percent agar and 0.1 percent Tween 80. The same series of dosages (grams or milliliters of material per kilogram of animal body weight) are used for all materials in this test. if no previous information is available on the compound or its analogs, a maximum dosage of 10 g/kg is selected to differ by a geometric factor of 2 from the preceding dose, i.e., l0, 5, 2.5, 1.25 g/kg. A sufficient number of dosages are given so as to bracket a 50 percent response. The animals are observed for several hours after dosing and daily over a fourteen-day observation period. At the end of this period the survivors are sacrificed, weighed and subjected to a gross autopsy. The results are tabulated and the LD is calculated by the method of moving averages using the tables constructed by Weil. [Weil, C. S., Biometrics, 8: (3), 249-263, 1952].

Samples received as liquids may be administered undiluted or as suspensions in aqueous Agar-Tween, de-

is believed to be relatively non-toxic, an initial maximum dosage 0f 10 ml/kg is selected and subsequent dosages are selected based upon the severity of gross signs of toxicity.

For organic phosphate anticholinesterase insecticides, the procedure is modified somewhat. The phosphates are readied for administration by preparinga solution or dispersion in corn oil (Mazola), the concentration of which is adjusted so that the total volume of the dose is 20 ml/kg (0.5 ml/kg in mouse) in every case. The initial solution is prepared by deciding upon the maximum dosage in mg/kg to be administered and preparing 50 ml. (10 in mouse test) of this solution of such a concentration that the desired dosage in mg/kg is delivered when 2 ml. (0.5 ml. in mouse test) of the solution is administered for g (20 g in mouse) of rat body weight. Serial dilutions differing by a factor of two are then prepared for each lower dosage level.

LD= values obtained by the above procedures are reported in the Table III below where it can be seen that compounds having the structure where R and R are methyl are generally much less toxic to mammals than derivatives in which R and R are hydrogen. Moreover, when these data are coupled with the insecticidal and acaricidal activity of the test compounds, it can also be seen that compounds having the structure where R, and R are alkyl, and at least one of X, Y and Z is a substitutent other than hydrogen, are preferred.

TABLE III LD Values For Test Compounds LD Values For Test Compounds R x l 3 Y P-SCH -s(ol -c- 2 n R R Z Structure LD S "Mice Rats (C H O) PSCH -SC H 5.6 1-5 H (C2H5O)2P scH sc 2 Q 67 1 2 n R3 R. A x Y z C2H -,O CZHS 1 CH CH, S H H H 88 CH:,() CH;; 0 CH CH S H H H 1 I7 28 nC -;H,S C2H5 0 CH cH o H H H 34 C2H5O C2H5 0 CH1, CH 5 H 4Cl H 79 CH;,O CH 0 cH CH3 s 3C1 4Cl H 200 CH;,O CH 0 CH cH s H 4C1 H 230 C2H5O CQH5 0 CH CH S 3C] 4C! H I00 CH O CH3 0 CH3 CH3 5 H 4Br H 220 cH o cH 0 cH CH3 s 2C] H SCI s00 CH O CH 0 cH 0H,, s H 2C1 3C1 500 *Vuluc reported in the literature.

MPLE 37 a petri dish. Ten third-instar Southern armyworm lar- Cut-Stem Systemic Test (Southern Armyworm) The compound to be tested is formulated as an emulsion containing 0.1 gram of test material, gram of Alrodyne 315 emulsifier, 0.2 ml. of acetone and 90 ml. of water. This is diluted tenfold with water to give a 100 ppm. emulsion for the initial test. A sieva lima bean plant with only the primary leaves unfolded is cut off just above soil level and inserted into a two-ounce bottle of lOO ppm. emulsion and held in place by a bit of cotton wrapped around the stem. The bottle is then placed in a ventilated box with the leaves extending outside the box, such that any possible fumes from the compound will be drawn out the end of the box rather vae are then added to each dish and mortality counts made after holding another three days at 80 F. and percent R.H. I

Mites The same procedure described above is employed in the mite systemic evaluation excepting that the sieva lima bean leaves are infested with mites, both adult and numphs, while the leaves are in the ventilated box. After 3 days the leaves are removed and examined under a microscope to determine percent mortality. Data obtained are reported in the Table IV below where it can be seen that the compounds of the present invention are systemically effective insecticidal agents.

TABLE IV l A l x ll STRUCTURE. 2

R o l Y Systemic Insecticidal Activity '7 Mortality Southern RI R2 A n R" R4 X Y Z Mites Armyworms C H O C H S 0 CH CH. H H H I00 n-C H S C H O 0 CH CH H H H 0 C H O C H S 0 CH; CH 3-Cl 4-Cl H I00 CH ..O CH; 5 0 CH CH; H 4-Br H I00 100 CH O CH 5 0 CH CH H 4-Cl H I00 100 (H S CH 0 0 CH CH H 4-Cl H 30 0 (H O CH 5 0 CH CH H 3C| 4-(l 30 90 than rising to affect the test leaves. After holding three We claim:

days at 80F. and 60 percent R.H., one leaf from each plant is placed on a moist filter paper in the bottom of 1. An organophosphorus compound having the formula:

x 1g 3 -Y I -SCH S(O) C n H2O Rh 2.

wherein R represents a member selected from the group consisting of C C, alkyl, C -C alkoxy, C- ,-C alkoxyalkyl, -C alkoxyalkylthio and C C alkylthio; R is C,-C alkyl; R represents a member selected from the group consisting of hydrogen and C -C alkyl; R is C -C alkyl; A represents a member selected from the group consisting of sulfur and oxygen; n represents an integer selected from 0, 1 and 2; X and Y each represent members selected from hydrogen, alkyl C -C and halogen; and Z represents a member selected from the group consisting of hydrogen, C -C alkyl, C -C alkoxy, cyano, halogen, C -C alkylthio, CCl CF and nitro.

2. A compound according to claim 1, 0,0-diethyl S- (a,a-dimethylbenzylthio)methyl phosphorodithioate.

3. A compound according to claim 1, 0,0-dimethyl S-(a,a-dimethylbenzylthio)methyl phosphorodithioate.

4. A compound according to claim 1, S-(p-chloro- 26 a,a-dimethylbenzylthio)methyl phorodithioate.

5. A compound according to claim 1, S-(p-chloroa,a-dimethylbenzylthio)methyl O-methyl, S-methyl phosphorodithioate.

6. A compound according to claim 1, S-(3,4- dichloro-a,a-dimethylbenzylthio)methyl 0,0-dimethyl phosphorodithioate.

7. A compound according to claim 1, S-(3,4- dichloro- ,a-dimethylbenzythio)methyl 0,0diethyl phosphorodithioate.

8. A compound according to claim 1, S-(p-bromoa,a-dimethylbenzylthio)methyl 0,0-dimethyl phosphorodithioate.

9. A compound according to claim 1, S-(p-chloroa,a-dimethylbenzylthio)methyl 0,0-diethylr phosphorodithioate.

10. A compound according to claim 1, S-(2,5- dichloro-a,a-dimethylbenzylthio)methyl 0,0-vdimethyl phosphorodithioate.

11. A compound according to claim 1, S-(p-cyanoa,a-dimethylbenzylthio)methyl 0,0-dimethyl phosphorodithioate.

12. A compound according to claim 1, S-(2,3- dichloro-a,a-dimethylbenzylthio)methyl 0,0-dimethyl phosphorodithioate.

0,0-dimethyl phos- 

1. AN ORGANOPHOSPHORUS COMPOUND HAVING THE FORMULA:
 2. A compound according to claim 1, O,O-diethyl S-( Alpha , Alpha -dimethylbenzylthio)methyl phosphorodithioate.
 3. A compound according to claim 1, O,O-dimethyl S-( Alpha , Alpha -dimethylbenzylthio)methyl phosphorodithioate.
 4. A compound according to claim 1, S-(p-chloro- Alpha , Alpha -dimethylbenzylthio)methyl O,O-dimethyl phosphorodithioate.
 5. A compound according to claim 1, S-(p-chloro- Alpha , Alpha -dimethylbenzylthio)methyl O-methyl, S-methyl phosphorodithioate.
 6. A compound according to claim 1, S-(3,4-dichloro- Alpha , Alpha -dimethylbenzylthio)methyl O,O-dimethyl phosphorodithioate.
 7. A compound according to claim 1, S-(3,4-dichloro- , Alpha -dimethylbenzythio)methyl O,O-diethyl phosphorodithioate.
 8. A compound according to claim 1, S-(p-bromo- Alpha , Alpha -dimethylbenzylthio)methyl O,O-dimethyl phosphorodithioate.
 9. A compound according to claim 1, S-(p-chloro- Alpha , Alpha -dimethylbenzylthio)methyl O,O-diethyl phosphorodithioate.
 10. A compound according to claim 1, S-(2,5-dichloro- Alpha , Alpha -dimethylbenzylthio)methyl O,O-dimethyl phosphorodithioate.
 11. A compound according to claim 1, S-(p-cyano- Alpha , Alpha -dimethylbenzylthio)methyl O,O-dimethyl phosphorodithioate.
 12. A compound according to claim 1, S-(2,3-dichloro- Alpha , Alpha -dimethylbenzylthio)methyl O,O-dimethyl phosphorodithioate. 